NEW NOISY M38A1 MUFFLER

[Ubique]

Hi,
Can anyone describe for me what should be inside an oval M38A1 muffler/silencer. I have recently replaced mine with what looks to me on the outside, a very well made repro. but on starting the jeep up it sounds like there's nothing in it, just an empty box.The nice sound of a Willys engine has been replaced but the chugging/banging of a tractor. Or is it my ears ?
It sounds as if theres no baffles in the muffler cancelling out that noisy " I've got a blown exhaust" noise that you get. I attched my old muffler against the flange of the new one ( So doubling the boxes ) and it sounded very quiet which is what I would have expected.
Or do oval mufflers supposed to sound like tractors to wake the enemy up ? Any replies would be very useful....Rather baffled what !
Ubique

[Joe Gopan]

You should be able to see a perforated pipe inside by peeking into the inlet. Sometimes the outlet is aimed just inside the right bumperette and the interference creates an annoying noise like the Jeep had just eaten a plate of beans. The RH lifting shackle can also cause interference with the exhaust.
Even in the good old Army days of GI Issue replacements, not all mufflers were created equal.

[Ubique]

Thanks for the reply. I have ordered a replacement and will update with with the result.
Ubique

[Ubique]

I've ended up buying a new muffler that is NOS that has a NATO stock number on it which indeed had perforated piping inside. The previous one didnt and it appeared to be a straight through pipe. The one I took off is different again but what is standard I dont know.
What I have discovered that the reverbaration from the rear bumperette was very distinctive at low rpm. So I cut off the end pipe from the old muffler and bolted the flanges together directing the exhaust gases down away from the bumperette. Ahh bliss...peace at last, it works a treat.

[Joe Gopan]

I've ended up buying a new muffler that is NOS that has a NATO stock number on it which indeed had perforated piping inside. The previous one didnt and it appeared to be a straight through pipe. The one I took off is different again but what is standard I dont know.
What I have discovered that the reverbaration from the rear bumperette was very distinctive at low rpm. So I cut off the end pipe from the old muffler and bolted the flanges together directing the exhaust gases down away from the bumperette. Ahh bliss...peace at last, it works a treat.

And that is what Army Motorpools did to M-38 and M-38A1 Jeeps for years. I still do.

[Zane Gross]

i use the m170 tail pipe tips on all mine, factory fit and looks great

[cmpman]

Above is the Cdn tail pipe extension modification for the M38A1s.

[Joe Gopan]

And that is the M-170 Tail Pipe.

[Joe Gopan]

I also save the outlets from worn out M-38/M-38A1 Mufflers to use as Tail Pipes. Did it in the Army too.

[Joe Gopan]

Anyone else having this problem?

[DJ]

"Anyone else having this problem?"

Saving old mufflers?

[Joe Gopan]

Anyone else encounter this?

[skyjeep50]

Both my M38 and M38A1 tailpipes have bolted on extensions made cut from old tailpipes and mufflers.

[Joe Gopan]

Kids like to stand on those extensions, the M-170 had a bracket to secure them to the rear cross member. The Extension originated on the M-170.

[JMZ421]

Once I found the correctly bent muffler, the only sound I get now on the M38 is the exhaust gas(pressure) hiitng the lifting shackle. That extension would eliminate that noise. John